Dielectric, impedance and conductivity properties of pristine and (Gd, Ru)-dual doped NiO nanoparticles

Abstract

This study investigates the synthesis of Ni 1–2x Gd x Ru x O nanoparticles, with different concentrations of Gd and Ru dual dopants, in an attempt to improve their dielectric and electrical properties. These samples are synthesized via the co-precipitation method, and characterized by various structural, methods, including the X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM), and Raman spectroscopy. The XRD patterns demonstrated the formation of single NiO phase, revealing the good incorporation of (Gd, Ru) in NiO lattice. The crystallite size decreased from 21 to 10 nm with increasing the dual dopants’ concentration. The TEM images demonstrated pseudo-spherical morphology of the Ni 1–2x Gd x Ru x O nanoparticles and the Raman spectra detected the fundamental vibrational modes of NiO. The frequency and temperature-dependent dielectric constants were augmented by the incorporation of the dual dopants, due to the induced nickel vacancies and larger surface-to-volume ratio. The Nyquist plots demonstrated depressed semicircles with smaller radii as the temperature and the dual dopants’ concentration increased. This was related to the enhancement of ac conductivity that followed different trends at room and high temperatures. The ac conductivity was tuned by varying the dual dopants concentration due to the ionic compensation mechanism, and the changes in the charge carriers’ concentrations and mobility. The correlation between the different dielectric and electric parameters suggested the dominance of the long-range conduction of the charge carriers. • Ni 1−x Gd x Ru x O nanoparticles, with x = 0–0.02, were prepared by co-precipitation method. • Gd and Ru dual dopants improved the dielectric properties of NiO nanoparticles. • Parallel RC circuits fitted the Nyquist plots with less R for higher dual dopants. • AC conductivity increased with dual dopants that were ionically compensated in NiO. • Gd and Ru dual dopants increased the interest in NiO for electronic applications.